Galileo is often held up as the hero of the Scientific Revolution.  While the supposedly backward Catholic Church ignored the facts of the “new science,” Galileo supposedly held his ground and insisted in the triumph of reason and the scientific method.

This is the story presented in most textbooks, and it is retold again and again as a model case of science triumphing over superstition.

The problem is that the story is much more complicated.  And frankly, when you look at the evidence in detail, you might come away with the conclusion that the Catholic Church was partially right to sanction Galileo.

To be clear about what I’m saying here, Galileo was simply not living up to the scientific standards of his time, and in many ways he was also violating what we think of as scientific standards today.

Before any Galileo fans have a knee-jerk reaction against this, try to find historical evidence that contradicts the gist of my argument below.  Also, I am not discounting the many, many, many significant contributions that Galileo made to science.  But in this one particular case, I’m not sure modern scientists really want to emulate him or claim him as the paragon of scientific rationality.

(Before I go on, let me first say that I have no connection to the Catholic Church, nor am I trying to defend it here.  I do NOT support some of the current strange movements to rehabilitate geocentric viewpoints, which some conservative Catholics seem to be getting behind.  In essence, my argument is that Galileo was wrong, but so was the Catholic Church.  If anything, the person closest to being “right” at the time in the modern scientific way was Johannes Kepler, whose views were not supported by either side in the trial of Galileo vs. the Catholic Church.  And of course, Kepler was a bit of a wacko mystic too, far from a modern scientist, but that’s a discussion for another time….)

A few summary points:

  1. Contrary to empirical evidence, Galileo insisted that he had found proof of the earth’s motion in tides.  His theory predicted that there should be only one tide per day.  This was obviously false, but he asserted his theory to be true anyway, and that it gave incontrovertible proof that the earth was in motion.  He considered Kepler’s claim that moon caused tides to be a useless fiction.  The tide theory was so important to him that he originally planned to title his “Dialogue on the Two Chief World Systems” as a book on tides, but the censors stopped him because… well, his theory had no evidence.
  2. Contrary to empirical evidence, Galileo refused to accept Kepler’s heliocentric model of ellipses for planetary orbits (which had been derived from the massive amounts of empirical data).  Instead, he stubbornly insisted on the Aristotelean notion that orbits must be in perfect circles.
  3. Contrary to common perception, a heliocentric theory with circular orbits (as Galileo insisted on) was not significantly less complicated than the Ptolemaic theory, or the Tychonic theory that was actually believed by many Catholic scientists of the time.  (Tycho Brahe’s theory kept the earth in the center, but had Mercury and Venus orbiting the sun.)  In other words, the traditional Copernican theory still required epicycles and fudging to make it work.  Kepler’s elliptical theory did not.  Galileo made a choice on his beliefs, rather than evidence.
  4. The “Occam’s razor” argument that is usually assumed—where Galileo was supposedly arguing for a significantly simpler system— is simply incorrect.  The reality is that Galileo’s support of the original Copernican system (with its circles as symbols of perfect motion) was based on nothing but his own preference, since data could not differentiate the Copernican system from the the Tychonic system, not empirically nor in terms of mathematical complexity.
  5. The first empirical evidence of the earth’s motion came about with the measurement of stellar parallax almost a century after Galileo’s trial.  In Galileo’s time, many scientists noted that parallax should exist if the earth moved, but their measurements found none, so observed empirical data at the time actually was biased against Galileo.
  6. Aside from all of this, Galileo’s theory went against common sense.  Common sense (supported by Aristotle and thousands of years of accepted scientific theory) observed that the earth was apparently stationary.  There were all sorts of logical and empirical arguments (most now discredited, but not really discredited by Galileo’s work) about what we should observe in the earth were in motion.  None of these effects were observed.
  7. Regardless of all of these holes in his theories, as well as his rejection of sound empirical data, and his unjustified unscientific choice to assert something to be true when he could not prove it or provide any empirical evidence to support it, he chose to write an inflammatory book that not only questioned the accepted theories, but also insulted anyone who went against his beliefs, calling his opponents “mental pygmies,” “dumb idiots,” and “hardly deserving to be called human beings,” among other things.  He didn’t present the arguments of his opponents fairly or accurately, and he claimed benefits for the Copernican system that were gross misrepresentations.

In sum, Galileo was an old arrogant man who pompously believed in his own theories when he couldn’t prove them, even when they went against not only empirical data in many cases, but also common sense.  In the cases where his theories even fit empirical data, they were not disguishable from the traditional ones according to experimental procedures at the time.

And he acted like a jerk to some really powerful people, misrepresented their theories (and his own), and relied on ad hominem attacks rather than empirical evidence.

For all of this, he was held in sumptuous apartments as a guest of the Tuscan Ambassador and then in a large apartment at the Vatican itself with his private valet to look after his food and wine while he stood trial (rather than actual heretics, who were thrown in dungeons).  And then he was sentenced to “house arrest” for a few years at an archbishop’s palace in a Tuscan villa, where he was given a rich apartment.

Actual heretics were tortured and burned at the stake.

After being a jerk and being called on it, Galileo didn’t say “and yet it moves,” but rather offered to go far beyond what the Inquisition asked in his recanting.  He freely offered to write new chapters to his book discrediting his own theories.  Why not?  At that time, his theories were pure speculation that couldn’t be proven from the data available.

One wonders whether his reputation would be different in history if he had been allowed to thoroughly discredit himself voluntarily.  Instead, as they had saved him from an embarrassment in the title of his book with the tidal theory, the Inquisition refused his request to write an amended chapter to his recent diatribe, thereby inadvertently securing Galileo’s reputation for posterity.


Any aspiring historians out there: please stop with the narrative about this trial being about a symbolic fight between science and religion.  In truth, it was about an old cranky man being a jerk to some important people, making some claims he couldn’t support, and being called on it.

As for those who would argue, “well, history vindicated him!”  Well, no it didn’t.  We don’t believe the planets move in perfect circular orbits in a very complicated motion that requires corrections of epicycles and such.  We don’t believe that tides are caused by the earth’s motion (at least not what Galileo meant by motion), and that they are proof of a heliocentric theory.  Galileo was a great scientist, but he wasn’t very interested in the complex details and mathematics of astronomical systems; yet that didn’t stop him from choosing which one he wanted to believe in and pontificating about it.

In the broad scheme of things, Galileo barely falls on the side of scientific progress in this trial.  This doesn’t take away from the other advancements he made to promote experimental science (which are very great and important), but in this particular case, he was the one pushing an agenda that required a kind of faith, while the Church was the one promoting calm rational thought that also agreed with empirical evidence available at the time and long-held philosophical truths.

Does that mean the Church should be allowed to censor his writings and force him to recant?  Of course not.  But that doesn’t mean that Galileo was a hero in this case.  He was just a jerk who was put in his place by more powerful jerks.